System Problems By Error In Detecting Frequency Of Apic Timer At Os Boot - Hitachi Compute Blade 2000 User Manual

With NTP, when delayed difference between frequencies is less than 0.05%,
the difference will not cause the system time to delay. For example, when an
actual clock frequency of CPU is 3000 MHz and the delayed difference is less
than 3001.5 MHz, NTP adjusts the system time.
If the system time delay is troublesome without NTP, use NTP.
3. To correct the system time when clock frequencies are incorrectly recognized:
The followings show the steps with and without NTP.
With NTP to adjust time
Reboot the system following the steps below:
a. Stop running applications.
b. Reboot the system.
c. Check if the CPU clock frequencies are correctly recognized using step 2
described above after the reboot.
d. Confirm that the system clock is correct.
With NTP to adjust time, the system time is adjusted at the system reboot.
Without NTP to adjust time
Reboot the system following the steps below:
a. Stop running applications.
b. Adjust the time using the following command.
Example: to set time to 15:00 7
# date –s "08/07 15:00 2009"
c. Reboot the system.
d. Check if the CPU clock frequencies are correctly recognized using step 2
described above after the reboot.
e. Confirm that the system clock is correct.
System problems by error in detecting
frequency of APIC timer at OS boot
Frequency of the APIC timer may be detected incorrectly at OS boot, which may
cause the following results.
 OS hangs up during the boot to fail to boot.
 Processing like nanosleep system calls pause execution for a short time, which
lowers the application performance.
 Commands for collecting information, such as "sar" and vmstat", which are
used to measure loading on the system, output incorrect results.
These problems are caused by an error in detecting frequency of the kernel APCI
timer at the OS boot.
When USB Legacy emulation interrupt occurs in frequency detection, the detection
process is delayed. Thus, the frequency may be different from the actual value.
However, since frequency detection is executed at OS boot, this phenomenon
cannot occur during the system operation.
th
August, 2009
1775